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@turf/random: fix randomPolygon generating polygons outside of the given bbox #2659

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Merged
mfedderly merged 2 commits into from
Aug 5, 2024
Merged

@turf/random: fix randomPolygon generating polygons outside of the given bbox #2659

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bd6a65c
fix randomPolygon generating polygons outside of the given `bbox`
nnmrts Jul 21, 2024
6a292b3
Merge branch 'master' into fix-random-polygon-out-of-bbox
mfedderly Aug 5, 2024
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23 changes: 22 additions & 1 deletion packages/turf-random/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -108,10 +108,14 @@ function randomPolygon(
} = {}
): FeatureCollection<Polygon, any> {
checkBBox(options.bbox);

// Default param
if (count === undefined || count === null) {
count = 1;
}
if (options.bbox === undefined || options.bbox === null) {
options.bbox = [-180, -90, 180, 90];
}
if (!isNumber(options.num_vertices) || options.num_vertices === undefined) {
options.num_vertices = 10;
}
Expand All @@ -122,6 +126,23 @@ function randomPolygon(
options.max_radial_length = 10;
}

const bboxWidth = Math.abs(options.bbox[0] - options.bbox[2]);
const bboxHeight = Math.abs(options.bbox[1] - options.bbox[3]);

const maxRadius = Math.min(bboxWidth / 2, bboxHeight / 2);

if (options.max_radial_length > maxRadius) {
throw new Error("max_radial_length is greater than the radius of the bbox");
}

// Create a padded bbox to avoid the polygons to be too close to the border
const paddedBbox = [
options.bbox[0] + options.max_radial_length,
options.bbox[1] + options.max_radial_length,
options.bbox[2] - options.max_radial_length,
options.bbox[3] - options.max_radial_length,
] as BBox;

const features = [];
for (let i = 0; i < count; i++) {
let vertices: any[] = [];
Expand All @@ -145,7 +166,7 @@ function randomPolygon(

// center the polygon around something
vertices = vertices.map(
vertexToCoordinate(randomPositionUnchecked(options.bbox))
vertexToCoordinate(randomPositionUnchecked(paddedBbox))
);
features.push(polygon([vertices]));
}
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